Resistant fabric



Oct. 1, 1963 w WHITEHEAD RESISTANT FABRIC Filed April 10, 1958 United States Patent 3,105,372 RESESTANT FABRIC William Whitehead, Qharlotte, N.C., assignor to Celanese Corporation of America, New York, N.Y., a corporation of Delaware Filed Apr. 10, 1958, Ser. No. 727,637 12 Claims. (Cl. 66-193) The present invention relates to a novel fabric and more particularly to a novel textile fabric or armor especially designed to resist penetration by high velocity projectiles or fragments thereof such as bullets, flak, and the like.

Since textile armor for acceptable efiectiveness must be employed in substantial weights such as 1.3 lbs. per sq. ft. or more and weaving fabrics of such weight designed for ballistic missile resistance is impractical, it is the accepted practice to weave fabrics in weights of 7 ozs./sq. yd. to about 17 ozs./sq. yd. and to laminate several layers by means such as sewing, resin bonding, or the like. One limitation in weight of woven structure is that maximum ballistic protection has been found when the interlacing yarns of the woven structure lie as nearly straight as possiblei.e. they bend and crimp in relation to each other as little as possible. This achievement becomes increasingly difiicult with progressive increase in weight and thickness of a woven fabric.

An object of the present invention is to provide an armor fabric in which the very large majority of textile yarn or fiber lies straight or crimpless, such fabric having considerably heavier weight and thickness than obtainable by weaving. Since fewer of the novel heavy layers of fabric are required for ballistic protection, there is less interference with permeability by air and body perspiration where such armor is not solidly bonded with resins, and thereby greater physical comfort results.

Other objects and advantages of this invention will be apparent from the following detailed description and clm'ms.

In accordance with one aspect of the present invention there is inserted into an otherwise light and open mesh knit fabric a heavy band or filling of high tenacity fibers or yarns caught into the texture of the knitted structure but in themselves flat, i.e. straight and substantially crimpless. The fabric is preferably warp knit on a double bed knitting machine forming a flat fabric, although circular fabrics can be formed and cut longitudinally or collapsed to a double thickness if a fiat fabric is desired. The filling-can be laid in parallel to the warp if desired but preferably is laid in transversely of the warp by intermittently stopping the two beds carrying the warp threads, laterally laying down the high tenacity filamentary material between the two beds, again actuating the beds to knit another course which locks in the filling, etc.

In the resulting structure the filling is flat rather than undulating or sinusoidal as in woven fabrics. As a result shocks applied locally can readily be propagated along the filling to permit the kinetic energy to be absorbed over a greater area of fabric. Consequently, few if any of the individual filaments are strained beyond their breaking points but at any rate too few to permit penetration by the high kinetic energy projectile. The ability to spread the absorption of energy over many filaments and large areas is enhanced by the low twist of the filling.

The warp conveniently is as light in weight as possible and serves principally only to hold the filling in place. They are knit into an open mesh or lace-like fabric so that as viewed from either face preferably at least 90% of the visible area comprises filling, i.e. in the absence of filling yarn most of the knit fabric area would be free of any yarns.

Preferably the warp yarns are formed of staple fibers but continuous filament warp yarns may be used although it then becomes desirable to apply a sealer such as wax, resin, or the like, at the areas to be cut in order to prevent ravelling. Alternatively, the warp yarns may be formed of solvent soluble or fusible materials such as cellulose esters or ethers, nylon, polyethylene terephthalate, or the like, so that the cut edges may be sealed by using hot cutting knives or by applying solvents. Since the warp yarns contribute but little to the absorption of kinetic energy due to their undulating and interlacing disposition they constitute only a small proportion of the weight of the fabric.

While cotton is well suited for use as the Warp yarn, man-made polymer yarns can also be employed, especially such yarns as can be caused to shrink considerably so that a more compact, tighter fabric can be produced. Representative warp yarns include yarns made of polyethylene terephthalate, linear superpolyamides such as nylon, re generated cellulose, cellulose acetate, and the like. Shrinkage can be produced in known manner either by chemicals,

by immersion in hot liquids such as water, or by steaming at elevated temperatures and pressures, e.g. steaming nylon or polyethylene terephthalate at 220 C. and 20 p.s.i.g for 30 minutes.

The filling yarns preferably are of high tenacities, in excess of about 4.0 grams per denier and preferably in excess of about 7 grams per denier; to achieve a given degree of ballistic protection lower tenacity fibers will requireprotective fabrics of greater weight than when using the preferred high tenacity fibers. Representative materials which can be used include nylon, polyethylene terephthalate and especially high tenacity regenerated cellulose such as is produced by stretching cellulose acetate 200 to 1300% in the presence of a plasticizing agent such as steam or a solvent, and saponifying, as is well-known in the art. Many ends may be plied into a single filling yarn by twisting but since transmission of the kinetic energy to be absorbed over a large area is favored by the absence of twist, the twist within a single end is preferably less than about 2 turns per inch and the twist of the plied ends is preferably kept below about 2 turns per foot. Accordingly, where a plurality of ends are to be joined into a single filling yarn it is preferably accomplished by twisting a light binder yarn about the parallel ends to hold them together. The filling yarns constitute at least and preferably from about to of the fabric weight with the balance made up of the warp and binder yarns. Generally, the filling should have a total denier of at least about 19,000 and 50,000.

The invention will now be described more fully with reference to the accompanying drawing, wherein:

FIG. 1 is a face view, on an enlarged scale, of a small portion of a novel fabric produced in accordance with the present invention, and

FIG. 2 is an exploded perspective view of an article produced by laminating several fabrics such as are shown in FIG. 1.

The fabric structure 10 shown in FIG. 1 is made up of a single sheet of warps knit together into a flat fabric with a heavy filling between the two faces of the fabric. In construction the fabric may be similar to that shown in US. Patent No. 222,370 or 2,249,650 with the exception that the warps of one face of the fabric are laterally offset from those of the otherface. Other fabrics of this type are those used in the constnuction of laundry pads as shown in US. Patent Nos. 2,158,006 and 2,178,633.

Referring now more specifically to the drawing there are shown loop chains i l, 12, :13 forming the front face of the fabric and loop chains 14,15 in broken lines forming preferably about 30,000 to the rear face of the fabric. The two legs 18, 19 of each loop making up the chains 11, 12, 13 on the fabric face extend rupwardly through the next higher loop in the same chain and then pass separately to the left and right to the rear face of the fabric (not shown) where they tie into the structure and then return to the front face in conventional manner. Filling yarn 16 is laid in transversely between the faces after each course is knit, the filling yarn com prising many parallel ends which are held together by a light binder 17 which is coiled loosely thereabout.

In FIG. 2, three fabric layers 10 are stacked with their I fillings successively offset at angles of 60 degrees. Spots of adhesive 20 are applied to the faces of two of the layers so that when pressed together a heavier but still flexible laminate results. Since each layer resists distortion in the direciton of its filling, each layer serves as a backing to prevent distortion of adjacent layers and a dimensionally stable structure results.

Lubricants or finishes may be added to the filling band of yarns or fibers or to the formed fabric to modify interfiber friction in the obtaining of desired ballistic performance. Water repellents and fungicides such as copper compounds, e.g. copper salt of 8-hydroxyquinoline, organotin complexes, 2,2'-methylene-bis-(4 chlorophenol), and the like may also be added either before or after knitting.

If desired, the fabric as formed may be knit to a woven backing of sufirciently open texture to permit penetration by the-knitting needles, the backing resisting the distortion which is otherwise possible with warp knit textiles.

Several layers of the novel textile armor may be stacked into a heavier structure with the filling yarns of adjacent layers extending at angles relative to one another. Assembly of the stacked layers can be effected by quilting, spot adhesion, resin impregnation and bonding, or the like By similar or equivalent procedures, one or more layers of the novel iarmor may be used in conjunction with other fabrics, films, metals and the like.

The following examples are given to illustrate the invention further.

Example I A flat knitting machine, with two beds spaced /8 inch apart and having latch needles over a width of 70 inches and with a vwarp beam carrying one warp yarn to be fed through a needle eye guide for each latch needle of one bed, is operated as follows: The needles are operated to knit a course, their motion is' arrested, a filling yarn is drawn from a tub and carried laterally across the full width of the machine between the spacedneedle beds, the needles are again actuated to knit the next course, their motion is again arrested,'the filling yarn is laid in laterally to bring it back to that edge of the fabric from whence it started, and the cycle is repeated.

Each warp yarn comprises a single endof 10 cotton count carded cotton, the warp yarns being spaced 3.8 to the inch and being knit in a 2:1 stitch pattern with rack over of one needle to the adjacent needle and back. The filling yarn comprises 24 parallel ends of 1600 filaments each 1 denier of regenerated cellulose having a tenacity of 8.0 grams per denier and produced by steaming, stretching and saponifying cellulose acetate; The 1 600 filaments of each end are held together by a twist of 0.8 Z turn:

per inch, and the 24 ends are bound together by three ends of 20 cotton count carded cotton twisted thereabout at the rate of 2 turns per foot. There are 13.3 picks per inch.

The resulting fabric has a inch gauge and weighs 3.9 pounds per square yard. The high tenacity regenerated cellulose filling is 94.72% of the total fabric weight, the Warp is 5.1% and the binder is 0.18%.

Example 11 A textile armor is knit on a double bed flat knitting machine operating as described in Example Lexcept that 4 the filling is fed to the filling traverse mechanism from a creel holding a cone for each end of the filling yarn. Each end is under equal tension, each is free of twist and the ends are laid down parallel with no combining twist.

The warp yarns are spaced 3 to the inch and each cornprises 2 plied ends of cotton, each end of 12 cotton count. The filling comprises 40 ends of nylon yarn having a tenacity of 7 grams per denier. Each end is of 840 denier and comprises 140 filaments. The resulting fabric has a gauge of inch, has 8 picks per inch, weighs 2.684 pounds per square yard and is approximately 90% nylon by weight.

Example III The process of Example II is repeated substituting as the filling yarn 21 parallel and untwisted ends of regenerated cellulose yarn having a tenacity of 8 grams per denier. The machine is run to produce 8 picks per inch along the warp. The resulting fabric has a gauge of /8 inch, Weighs 2.8 pounds per square yard and is approximately 95% regenerated cellulose by weight.

It is to be understood that the foregoing detailed description is merely given by way of illustration and that many variations may be made therein without departing from the spirit of my invention.

Having described my invention, what I desire to secure by Letters Patent is:

1. A protective fabric comprising a two-faced warp knit flat fabric with a filling between the faces, said filling comprising high tenacity continuous filamentary material having a twist of less than about 2 turns. per foot.

2. A protective fabric as set forth in claim 1 wherein said filling has a tenacity in excess of about 4.0 grams per denier.

3. A protective fabric as set forth in claim 2 wherein said filling comprises at least about of the weight of the fabric.

4. A protective fabric as set forth in claim 2, wherein the warps are composed of staple fibers to prevent unravelling following cutting.

5. A protective fabric as set forth in claim 2, wherein the filling comprises a plurality of ends.

6. A protective fabric as set forth in claim 5, including a binder yarn twisted lightly about said ends to hold them together.

7. A protective fabric as set forth in claim 3, wherein the filling comprises high tenacity regenerated cellulose.

8. A protective fabric as set forth in claim 3, wherein the filling comprises nylon.

9. A protective fabric as set forth in claim 3, wherein the filling comprises polyethylene terephthalate.

10. A protective fabric as set forth in claim 3, wherein the total denier of the filling is at least 19,000.

11. A protective article comprising a protective fabric as set forth in claim 2 and a fabric backing connected therewith to prevent distortion of said fabric.

12. A protective article comprising a plurality of layers 7 of a proteotive'fabric as set forth in claim 2, said layers being secured to each other.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PROTECTIVE FABRIC COMPRISING A TWO-FACED WARP KNIT FLAT FABRIC WITH A FILLING BETWEEN THE FACES, SAID FILLING COMPRISING HIGH TENACITY CONTINUOUS FILAMENTARY MATERIAL HAVING A TWIST OF LESS THAN ABOUT 2 TURNS PER FOOT. 